What makes a good research proposal?
Geesh come on. Author is rather idealist.
The #1 most important thing in research proposals is making good images. No one cares about the text as long as it fits the proper mold. But the images that concisely convey the novelty of the work are worth $$$.
(Source: advisor and I had over 80% success rate in field that averaged <20% over 16 proposals).
Regarding the writing itself, see Larry McEnerney’s lecture The Craft of Writing Effectively:
This is very concise and well-informed. Here are three things that I really liked:
[1] A discussion of risk and mitigations, last paragraph under "Secondary questions".
This is an excellent way to squarely confront possible objections by reviewers. It shows you understand what problems might come up, and shows the mitigation(s). It can be presented as a "risk list" with possible mitigations for each (a two-column table). Risk mitigations can include alternative technical approaches, or schedule adjustments, or descopes if the sponsor allows it. More formally, columns for a qualitative likelihood of the risk being realized (1-5), and a severity if it is (1-5).
Think broadly about risks. "Postdoc cannot be found" is a risk. "Experimental data contaminated by systematic effects" is also a risk.
[2] Advocating for a top-level statement, within the first couple of paragraphs, of the problem to be solved, why it matters, and how it will be done. If you can't do this in two or perhaps 3 sentences, you are confused and should think more carefully about what you're proposing. I'd go even farther and say one should aspire to have the first 3 words of the proposal be "We propose to ...", with the whole thing laid out in one sentence.
Do not have the first couple of paragraphs be problem background. It's not a science paper.
[3] Adapt narrative to the proposal format (OP under "Adapt to the funder"). Those categories in the template are there for a reason -- to simplify comparing proposals -- but you have to take some license to be sure you're not repeating, and that the document still is readable from top-to-bottom.
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My own bad or poorly-conceived proposals have signaled trouble by repeating themselves -- same or similar paragraphs or long sentences in the abstract, then in the introduction, then in the motivation or conclusion. This either indicates a bad cut-and-paste job, or that thought has been suspended.
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The summary mentions generating excitement. One way to do that is to think about storytelling techniques.
A classic storytelling technique is the "undiscovered country" plot, e.g. a 2D plot of (say) wavelength vs. telescope observing time that illustrates why having (say) a UV telescope with very long integration times will enable a new class of objects to be seen.
Another "win story" can be developed by answering "why now" -- what combination of data and technical know-how makes this the right time to do this work? Basically, inevitable that someone must do this right away.