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TOPIC: New Motors from TSP Modelar

New Motors from TSP Modelar 1 week 4 days ago #1556

  • Terry Kidd
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Here are the graphs of the measurements I made last week. Just to be clear, these are for each of the new CE standard Tendera motors, namely:
L1, L2, L2HP, L3 and L4. I did three runs of each type and as you will see the performance for motors is pretty consistent.

Average 109mN 13.5secs
Ave. 196mN 17secs.
Ave. 351mN 16secs.
Ave. 539mN 18secs.
Ave. 1178mN 17secs.

As a slight difference from previous published graphs the graph starts at the first second after the start of thrust AND a full second has elapsed. In each case I set the test rig ready, light the new green fuse and let the rig measure the data. The data gets sent to my lapbook so I can capture it and save it in a spreadsheet. The graphs are then drawn, automatically, by the spreadsheet. The rig is calibrated by turning it through 90 degrees so that a (known) hanging weight deflects the strain guage in the same sense that the measured thrust does.

In the next days I'll try and make some measurements of L2s that I've modified for a wider nozzle diameter. (2.1mm, 2,2mm etc) I'm looking forward to seeing how the L2 behaves with such a modification.
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New Motors from TSP Modelar 6 days 1 hour ago #1557

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The latest email from the Vintage Model Company had this:


they can now be ordered and delivered by courier:



This is all to the good, and VMC are to be applauded for this venture which is (for them) into unknown territory.
It is unfortunate then, that they spoil it with this comment:
"They are (in our humble opinion) quite expensive. We've cut the recommended price as low as we can and I think we're cheaper than our European counterparts, but any lower and we wouldn't make any money."

I got quite fed up with these sorts of comments, then about Rapier motors, at meetings. especially as they tended to be made by guys as the got into their Range Rovers, on the back of which was a sticker proclaiming the driver belonged to a posh golf club!
That our motors are expensive is a judgement, not an objective fact. Expensive in relation to what? :woohoo:
When you consider all the research that has gone into these motors, the background expertise, the extensive testing and the cost of certification, these motors represent excellent value.

Yes, they do cost more than Rapiers, but TSP motors come in nice packets that give pride of ownership and I trust them more than Rapiers.

If you want to fly rocket planes, with all their attendant thrills and frustrations today then there are two options:
(a) TSP motors
(b) genuine Jetex.

I do both, usually sourcing Jetex stuff from eBay. I know which is the cheaper (and less frustrating) option!B)

Rant over.:kiss:
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New Motors from TSP Modelar 4 days 16 hours ago #1558

  • BigGuy
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Actually, flying rocket planes can get quite expensive, here's why.

Way back when we were flying Rapier planes at Taft, we would go through many motors in a day. After a flight it was a simple matter to change out the used motor for a new one, light it off and make another flight. Most of our models had sheet balsa wings, or were scale replicas, the glide wasn't the best so we didn't have far to walk to retrieve. One could easily fly a dozen flights in an hour, or until the supply of rocket motors ran out..
Here's hoping someone can find a way to import the new motors into the USA. I will be first in line to buy some.

John in Prescott, Arizona

Roger adds:

Great to hear from you John, and you are right about getting through a lot of motors in a day! A good session with Rapiers could easily put you back 60 pounds or so. But it is a lot of fun and still cheapr than, say golf or fly fishing
:lol:

You could contact Bernard Guest This email address is being protected from spambots. You need JavaScript enabled to view it. importing TSP motors into the US. There surely (don't call me Shirley) must be a way.:dry:
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New Motors from TSP Modelar 1 day 18 hours ago #1566

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Here are some test runs I made today with L2s modified with incremental nozzle sizes.

The 2.4mm nozzle hits the sweet spot of 139mN for 18 seconds. (Or, 1/2 oz of thrust if, like Darth Vader, you prefer Imperial measure. ) That is the notional rating of a Jetex 50 anyways.

But I was seeing some burn throughs. I'm going to try again soon with several motors modified to 2.4mm and see what happens.
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New Motors from TSP Modelar 1 day 17 hours ago #1567

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Oops, I've now been advised by Piotr that the nozzle starting size is 2.2mm so my first three plots can be ignored! The nozzles are effectively unmodified.

So here's another plot with the unmodified traces removed.



And I'll do a few more tests with several motors with 2.4mm nozzles.

Roger adds: I measured the noxxle diameters of my CE TSP L-2 motors with a micrometer. The range was 2.08-2.11, say average of 2.1 mm. This would explain why your trace for '2.2mm' is a bit down on the unmodified motor and 2.3mm looks 'just right.

The consistency is impressive!

Did the motor casing actually burn through completely in a way that would endanger a model?
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New Motors from TSP Modelar 1 day 28 minutes ago #1568

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I had an interesting communication from John Emmet, who is looking to make an igniter for TSP motors and old (and sometimes hard to start) Rapiers:



Above: John's well regarded and still-available. Jetex igniter.

John writes
"1. It looks like the electric igniter problems that people are having are down to low thermal energy rather than low temperature. Unfortunately, there are conflicting requirements here, as you need good thermal conductivity down the probe in order to get the heat into the fuel. Unfortunately high electrically conductivity is needed for the batteries sake, and that comes with poor thermal conductivity. Copper has a thermal conductivity 20 times that of (say) Kanthal heater wire, that is why the old coaxial igniters had a copper core, but with 3 volt batteries you need at least 5 x that resistance.

2. The good news comes from the below longitudinal sections of a TSP L-1 and a Rapier;
Here you can see that both have a 1.4mm diameter nozzle, which gives us twice the area of any suitable Jetex probe. Also any TSP/Rapier probe only needs about 7mm depth reach, as apposed to 1mm diameter with a 20mm reach needed for a Jetex 50C.



3. A most professional touch in the nozzle of the TSP is the narrow layer of (probably) black powder as an ignition booster. You can see its effect in the start up sparks, as well as the thrust peak.

I do wonder if an electric igniter is really essential if the fuses turn out to have no problems associated with them? Of course any open flame close to tissue/dope is bound to be dodgy, so I will be going ahead anyway."

I replied:

" many thanks for this, it's good stuff. You have a good point about temperature vs. thermal conductivity : A 30 SWG Nichrome element gives a healthy orange/yellow glow in a Cord Zap with two quality AA batteries, but (in my experience) hopeless at igniting the Rapier propellant. 28 SWG is a good compromise. 26 SWG is better but (a) you need more batteries, (b) the Rapier nozzle is so narrow it's difficult to get the heating element down the 'ole.The Vintage Model Company) have a 2 mm plus nozzle diameter so 26 or even 24 SWG Nichrome would work with these.
That TSP motors have a black powder as an ignition booster. This reflects Piotr's experience with motors for 'ballistic' model rockets. I'm not sure they are such a good idea for our sorts of models though. Troughs will need to give your Hawker Hunter adequate protection. When I first ignited a TSP CE motor the initial squib-like exhaust made me jump! Scary!"

Inspired by john, and blow the expense, I then cut a CE TSP motor in half:



Note the fuse fits the nozzle 'only just'.



Note the different colour (pink) of the CE propellant from the earlier motors black). Note also the black powder ignition booster.

John then asked, "Is an electric igniter really essential if the fuses turn out to have no problems associated with them? Of course any open flame close to tissue/dope is bound to be dodgy, so I will be going ahead anyway."

I answered,

"I didn't find poking the CE green fuse in the nozzle and getting a good contact that easy, So yes, we do need one"! :)

I look forward to what John, a very clever engineer, comes up with. B)
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