TOPIC: Duration Competitions for TSP Powered Models

This posting could go equally in 'Building' but as the emphasis is mainly on flying I'm putting it here. The consistant and reliable performance of TSP motors makes a 'rocket duration' class attractive and viable for the first time in years. Brian Lever of Peterborough MFC is especially keen on this, and has organised competitions to take place at the BMFA centre at Buckminster. To this end, not a few hardened competition flyers have dusted off their rocketry skills and making models in preparation for what we hope will be the popular 'Open' event.

Bert Whitehead has been busy building 'Snowflakes', a Ron Armstrong design published in the Aeromodeller in 1960:


Above: originally for Jetex 50, Bert has adapted his for TSP L-2 power:







Above: Bert has built three Snowflakes. Note the (very necessary, says Bert) timer and dethermaliser.

Bert writes:

"I really hate to alter designs by the old masters so my Snowflakes are not Snowflakes at all but I've used the dimensions to give me a starting point because this is all new to me. I've made 3 because I expect to loose them at Ferry Meadows even though I've built into them home made viscous DT's. (Silly Putty). I've built them for L2's with a motor tube made with 5 layers of ordinary photocopier paper (pva glue). The nose has tough foam from Flip Flop shoes soles for safety. Wing Trailing Edge has Bamboo shavings capping from kebab skewers for a bit more strength. Tailplane pivots on a 1.5 mm bamboo hinge pin with 2 plastic tubes bound to the L E. Covered with Esaki and Easi Dope over all the model to try to waterproof it a bit. Wing and TP bands cut from balloon necks. Balance point 1" from Trailing edge. Too heavy at 26 Gms but glides OK. Not flown under power yet"

Brian Lever, believing a 'good big one will beat a good little 'un' has built a Star Jet, to be powered by an L-3 (or, says Brian, an L-4!)



Others might want to fly a smaller model powered by an L-1:



Above: yet another Snowflake!

A ‘one motor’ duration competition, one where the results better reflect the competitor’s design, building and flying skills, is also an attractive possibility. The proposed rules are shown below:

PMFC TSP L-1 Rocket-plane Duration

1. Models can be of any type of construction, propelled by a single reaction motor of the L-1 type (see (3) below).
2. The contest is open to all who pay and register upon arrival. Contestants must be current BMFA members.
3. Only the latest ‘CE L-1 type TSP motors, be supplied by the organiser, will be allowed. and may not be modified in any way.
4. All motors shall be mounted in a tube or clip securely attached to the model. Note the motors have a diameter of about 10.2mm. Mounting tubes should have a wire retaining clip to prevent the motor from slipping out during launch or separating from the model during the gliding phase of the flight. The Contest Director (CD) reserves the right to bar any model he considers unsafe.
5. Models will be launched by hand; no catapult assisted launching is permitted. If a competitor is using a fuse, the model may not be launched before motor is ignited.
6. An official flight occurs when the model remains in the air for 15 seconds or more. The maximum will be set on the day, taking into account conditions and flying site. A competitor’s best three from five official flights will count towards the final score. Flights of less than 15 sec will be classified as an attempt. Re-flights in the event of, for example, a collision of models will be allowed at the CD’s discretion.
7. Scoring time shall be the total elapsed time of three official flights in seconds, with all fractions of a second first dropped.
8. In the event of more than one competitor posting a maximum score on three flights a ‘one off’ unlimited ‘fly-off’ will decide the winner. No ‘attempts’ will be allowed in the fly-off. The score will be the total flight time or time to OOS.

These are I hope sensible and uncontentious, but a few comments may be necessary to answer any questions the reader may have.

The TSP L-1 motor went through quite a few iterations of size, formulation and hence performance during development, but now consistently produce a thrust of around 100 mN (a third of an ounce in old money) for 11-12 sec. This is more than enough to give the right model a sparkling (!) performance, models should stay in the field and the proposed max is a challenge without thermal assistance.

Luke Goymour has already built models, a Spacejet and variations of Howard Metcalfe's lovely 'QT', for this event:



I hope we will see many different models, old and new, flown in these events!

PMFC held its first round of free flight competitions yesterday, which included (open) rocket duration. Luke Goymour reports:

"I went along to Ferry Meadows today for the first round of Club competitions. Three of us flew in Rocket Duration, very successfully. I messed up my first flight (was still triming and model (QT) spiraled in after 13 secs. But sorted it out for 2nd and 3rd flight and maxed comfortably.

Brian Lever flew his Fizz Whiz and Bert Whitehead flew his snowflake; they were sensible and spent more time trimming and maxed out. Our models were certainly the "show piece of the day" and the QT got a lot of attention. Brian and Bert were using pre-CE TSP L2s and I was using CE L1s (I hadn't got round to assembling my lighter yet!). Bert has built a lighter with 5 cells, that was very impressive and worked reliably".

Bert was also thrilled with his day. He writes:

"Every thing went fine yesterday with the Snowflake. Went really high and fizzing all over the sky with loops and stalls etc. Still in one piece. Really do need a D/T or you're bound to loose it. The igniter worked perfect and so powerful that I doubt if you need to drill out the motors. The three of of us and created a lot of interest".

Brian writes:

"You will be delighted to know the first open rocket competition took place yesterday afternoon. Conditions were rather blustery and cold!I had quickly built the Brian Waterland Fizz Wizz design created by him some 32 years ago, which is rather more suitable for the venue than the large KK Skyjet. In a test flight the Fizz-Whuzz turned left; this tightened into a spiral and a crash, which broke the fuselage in two places. Cyno to the fore, and the model was glued back together. However, it was discovered not too accurately.
Using my ( oh dear I hear you sigh) clip I compensated with left motor thrust.

I used a lowish power L-2 the first competition flight the model flew in beautiful wide right circles to good height and easily achieved the 40 second max. For the second flight I used a TSP L2 HP. The model flew until a dot in the sky and was timed at well over 90 seconds.The third flight repeated the second using the same motor combination.

Bert had also maxed out using TSP L1 motors in a modified Snowflake. Luke Goymour missed out on the Fly Off with one flight of 13 seconds with a very beautiful small design [the QT]. Both his two other flights maxed out from great height.
In the Fly Off Bert unfortunately crashed from launch for a 5 second flight. My Fizz Wizz ( again with TSP L2 HP ) rose once more in wide right hand circles to a huge height to win the Fly Off and the first Open Rocket competition of the season.

All in all a great first competition . Both electrical and fuse ignition were effective (the former more so than the latter) and all motors ran reliably and with smooth power delivery.

We are looking forward to Round two of Open Rocket next month. All Open Rocketeers welcome!".



Above: Bert launches his 'Snowflake' for another max.



Above: Brian launches his Fizz-Whizz. In contrast to the Snowflake, but like the QT, it is an all-sheet design.



Above: Brian's Fizz-Whizz for L-2 power. Simple, robust and effective. I do wish, though, he would fit a proper motor mount! Also, it may need a dethermaliser!



Above: I hope this happy trio of competition flyers (from the left. Brian, Bert and Luke) will soon be joined by others!

Luke has added this to his contest report:

"The weather was overcast and breezy with speeds of 10-15 mph. This was 10 mph more than was predicted 8 hours earlier! Oh well, it was the same for everyone.
Bert, alas, did not win; he should have, but his fly-off flight was scuppered by a strange motor malfunction. We are not sure what happened, it appeared to be some kind of miss-fire. Bert launched, then the motor stopped, and then started again a second later and looped his model into the ground after 5 secs.. There are no 'attempts' in a fly-off. Nevertheless, Bert retrieved his model and with admirable panache launched againwith the motor still running. He did a minute and twelve seconds out of sight!
Bert and I went to look for his Snowflake after the competition. We found it on the correct the line of sight. Brian, winnwer of the fly off, managed a very competent flight spiralling nicely upward in wide circles and transitioning into a gentle glide for around a minute.

Club competitions (unlike the Flying Aces) are to 'Open Rules' so people are free to use whatever motors they want (even an L-3 or L-4!). But I am thrilled that once trimmed the QT with a L-1 is just as competitive as the bigger L-2 powered models. Being small and cheap to build, they are are pretty disposable to thermals, so I don't worry about a d/t)
The suggestion about increasing distance from the wing to the motor mount on the QT (or any similar model) is a good one as, even with metal tape placed at strategic points, the tailplane does get attacked a bit by the rocket exhaust."

Brian Lever, the worthy winner, has sent me some clever details about his motor mount that allowed him flexibility in trimming for the power of a TSP L-2HP:

"Just a couple of points regarding the motor clip:
Each TSP L2 HP used in Fizz Wizz had the motor wrapped in three turns of green electrical tape at the exact point to provide the correct c.g.This also ensured the motor was very securely held in the clip. By pure accident I discovered that the hot motor heats up the tape to the point it welds itself to the clip. There is thereforw absolutely no chance of the motor leaving the clip during or after flight.

On releasing the spent motor at the end of each flight it is necessary to open up the clip by hand to release the tape and thus the motor.
I have always used clips during the trimming phase of a rocket powered jet as it enabled me to quickly introduce left thrust after the initial crash [and gluing together again] and ultimately win the competition. When I am completely happy with the trim I will introduce a motor tube with the required offset.
To reiterate: I am still a firm proponent of using clips during the trimming stage because of the ease of thrust line and c.g.adjustments".



Above: Brian's motor clip. Note the electrical tape. Leve this off at your peril!

Brian Lever has kindly sent me details of Brian Waterland's 'Fizz-Wizz'.



Above: the Fizz Wizz is a simple but effective all sheet model. Designed twenty years ago for a Powermax Jet-X 50, it flies well with a TSP L-2HP. If reduced in size, it would, I think, be equally competitive with TSP L-2.

Brian comments:

"Please note I increased the wood sizes; wing 3/16", tailplane/fin 1/8". A thicker wing obviated the need for antiwarp strips. Using decent wood (not Depron) the model weighed 23.5 grams less motor and motor mount (clip). Perhaps a D/T would be a good idea!".

Please tell me if you would like a copy of the plan.

The QT also dates from about 20 years ago, I scaled it up to made a bigger version of it at 16" in balsa for a Jetex 50, that went well. Sorry about the poor pic but it is from an early digital camera.



I also designed a model called Jetsam for the Rapier L2 but only flew it once on a trim test flight with a L1 and nearly lost it! It will need a DT with a TSP L2, it will really go with one. I had a 'silly putty' DT fitted for its one and only flight outdoors but didn't bother using it for just a trim flight, ooops. I did fly it indoors but that is another story. Balsa fuselage and Depron surfaces, note the front of the fin is lined with foil as is the top of the wing root.



Roger comments:

the Jetsam looks very tasty indeed. If built to, say 15" span it woul suit a TSP L-1. Howard, could you provide a drawing with dimensions. Please, pretty please!

Yes please, Howard. Send us a plan and I'll build it!